Conventionally, excavators comprise a beam pivotally mounted at its proximal end to a support for angular movement about a horizontal axis and an arm pivotally mounted at its proximal end to the distal end of the beam. In some instances, the pivot connecting the distal and proximal ends of the beam and arm is at the extremities of the respective beam and arm and the power-operated cylinder is disposed between the proximal end of the beam and intermediate the ends of the arm to effect articulation of the arm relative to the beam. In other instances, the arm is pivotally mounted intermediate its ends to the distal end of the beam and a power-operable cylinder is disposed between the proximal end of the beam and the proximal end of the arm. In both such structures, the shovel or backhoe is pivotally mounted to the distal end of the arm and there is power-operable means mounted to the arm for effecting movement of the shovel or backhoe. The disadvantage of such structures is that there is minimal mechanical advantage available for driving the shovel or backhoe, with the consequence that when resistance to operation is high, excessive stresses are developed in the beam and linkage which results in breakdowns. It is the purpose of this invention to provide an improved construction which will afford maximum mechanical advantage for the power input with minimal development of destructive stresses in the structure. Further objects are to provide a structure which will afford maximum depth range and is so structured as to enable the use of a shovel or backhoe with minimal conversion.